Flickboard is also worth checking out if you like this style of typing. It’s on F-Droid.
The dev compares them like this in her README:
Why not MessagEase?
It’s proprietary, and suddenly started requiring a subscription.
Why not Thumb-Key?
Back in the day, Thumb-Key didn’t support MessagEase’s more advanced gestures like circles and U-bends.
They do now, so this section is mostly historical, but FlickBoard’s detection might still feel different, in ways that people may or may not prefer.
ash@piefed.ca 1 day ago
I have used Flickboard too and I like both of them.
Flickboard is more advanced and supports a lot more customization. For example, it has macros which expand to symbols and text. You can create shortcuts for your email, math and currency symbols etc.
IME thumb-key is minimal, updated more frequently, and looks better out of the box. So I prefer it.